Pittsburgh to get warmer, wetter in next decades

about insects emerging early and birds arriving late, and in the waters, insect larvae hatch being out of step with trout, says Court Gould, executive director of Sustainable Pittsburgh.

Local climate experts say farmers and gardeners will have to grow different strains of crops to keep up with the shifting seasons, and the cost of milk could rise as warmer temperatures impact the seasons for local dairy cow farmers.

Warmer temperatures and more heat waves would test the city’s infrastructure and increase consumer utility bills too, with greater demands on the electrical grid.

The danger that climate change poses for urban infrastructure is something that Costa Samaras has dedicated his professional life to. As head of Carnegie Mellon University’s Center for Engineering and Resilience for Climate Change, he is at the helm of one of the first programs in the nation that focuses on adapting infrastructure for climate change.

“Small increases in the temperature — a couple degrees — doesn’t sound like a lot, but we’ll be feeling the effects pretty heavily here in Pittsburgh,” Mr. Samaras says. “We’ll have more heat waves. We’ll have lots of electricity use during that time, so we might have a little more stress on our power grid. Locally, in our homes, folks will run their air conditioning more.”

Temperature changes in Pittsburgh are already taking place. Government weather data shows the city has warmed steadily in the past half century. The 2000s, on average, were about 2 degrees hotter than the 1960s.

The world, on average, has warmed by about 1 degree in the past 50 years, but that rate is accelerating; in the next three decades, it will get another degree warmer. Sixteen of the 17 warmest years on record have occurred since 2001, according to the National Aeronautics and Space Administration. The global temperature in 2016 broke the record set by 2015, which shattered 2014’s record, and the likelihood of that happening by chance is about 0.8 to 1.5 percent.

The number of snow-covered days in the region has fallen and will continue to decline over the course of this century, climate projections show. Snowmaking will become so difficult that Pennsylvania might no longer be able to support a skiing industry.

“If we continue business as usual, which really we would expect the carbon dioxide emissions around the globe to go up, it would get noticeably warmer decade by decade,” says atmospheric chemist Neil Donahue, director of CMU’s Steinbrenner Institute for Environmental Education and Research. “It really is warmer than it used to be — progressively, systematically warmer.”

Floods and storms

Half of Pittsburgh’s top10 extreme rain events on record have occurred in the past two decades.

But what will happen when it gets rainier?

Imagine a Pittsburgh where there’s a constant fear of flash floods like the one in 2011 on Washington Boulevard, that killed four people; a Pittsburgh where small decisions about floodgates and stormwater runoff could save lives.

That’s a reality that isn’t far off. Scientists project that the frequency of heavy rain will continue to increase throughout the century in the Northeast, and that storms will be stronger — which is especially concerning for cities with many hills and valleys like Pittsburgh.

It’s already rainier in the region. Heavy rain events in the Northeast spiked more than 70 percent between 1958 and 2010, the highest regional increase in the country. More than a third of all thunderstorms recorded in Allegheny County since 1955 have occurred in the past six years, including a recordbreaking 66 in 2013, according to the National Oceanic and Atmospheric Administration’s database of storm events.

And that’s worrisome to several local climate experts, who warn that the Pittsburgh area’s stormwater systems — which are engineered to remove water from roads and sidew a l k s after storms — aren’t prepared for heavier rainfall and more frequent storming.

“Most of the stormwater management plans have been developed by lawyers and politicians, and they don’t understand the science,” says Louise Comfort, director of the Center for Disaster Management at the University of Pittsburgh. “Literally, it’s a problem that needs hydrologists and meteorologists. Until then, all of the downstream small communities are going to continue to get flooded.”

Pittsburgh’s sewer system capacity is particularly concerning.

A stormwater report from the RAND Corp. found that 11 billion gallons of water overflowed from Pittsburgh’s sewers from 2004 to 2013, a number 15 percent greater than estimated.

And with the amount of average annual rainfall increasing, sewer overflow could be 15 to 40 percent higher in the next decade, says Jordan Fischbach, the report’s author and codirector of RAND’s Water & Climate Resilience Center.

This could shorten the amount of time people can spend in the rivers and could signal a serious issue of public health if there’s an increase in sanitary sewer overflows, which release untreated sewage from the system.

Local climate experts worry that residents will have to bail out their basements several times a year from sewer system backups, unless municipalities put into place green infrastructure that can absorb and redirect stormwater before it clogs the system.

Mr. Samaras says adding green infrastructure can cool down a neighborhood and suck up pollution and flood water, which could trickle to downstream communities at an alarming rate.

A recent Army Corps of Engineers study predicted that stream flows in the eastern part of the Ohio River Basin — including Pittsburgh — will increase by up to 50 percent in the next few decades, which will challenge the stormwater management systems in communities like Millvale, where 90 to 95 percent of water that flows through the local stream comes from outside the borough’s borders.

“The city is certainly pushing forward on these techniques, this green infrastructure, but there’s resistance from other portions of the area,” Mr. Fischbach says. “As one big connected system of 83 municipalities, it makes it tougher and more complicated to do this in a regional, systematic way.”

The complex maze of municipality borders and watershed maps is a big challenge to the regional fight against climate change, but no matter what — from the experts at Carnegie Mellon, to the offices of Sustainable Pittsburgh, to Millvale’s borough building — there’s a consensus that communities should be preparing for climate change right now.

“It’s not like you ‘believe’ in gravity. Climate change is not something you ‘believe’ in or don’t, if you’re being intellectually honest,” Sustainable Pittsburgh’s Mr. Gould says. “We have to move to, ‘what can we do?’ ”